My tank was aluminum, so I didn't want to use any chlorine in it. It was never a problem, though. During the sailing season, I had enough throughput that the water stayed fresh and sweet.

When I de-commissioned the system (winter in the States and summer in the Caribbean), I would pump as much water as possible out of the tank and then vacuum out the rest with a small shop vac that I kept on board. The tank was then essentially dry, with no chance of any growth. For the tubing, I would blow out the water with a compressor.

When re-commissioning, I'd mix up a cup of Chlorox and water in a five gallon bucket, dip the water pump's inlet hose into the bucket and open the various taps, letting the water run until I smelled chlorine. After 4-6 hours, I'd flush it out. Never had any issues with crud growing in the system.

When re-commissioning, I'd mix up a cup of Chlorox and water in a five gallon bucket, dip the water pump's inlet hose into the bucket and open the various taps, letting the water run until I smelled chlorine. After 4-6 hours, I'd flush it out. Never had any issues with crud growing in the system.

That's a neat idea. Like you, I drain and dry the tank at the end of the season. No bugs. I never gave much consideration to the piping, but since I have Ts and valves for sucking in glycol for the winter, that would be quite simple (suck in bleach solution in the spring while blowing the glycol out). Sertainly smart for folks with aluminumtanks, and very easy if the winterizing Ts are in place.

Truth is I've never had a problem with growth (cut a section out just a few weeks ago; clean as any pipe at home) because I follow your other practices and I use glycol strong enought to function as a biostat.

How long do the candles go between cleanings? How many cleanings do they survive? Any pre-filtration?

We clean it about 1x month, give or take. It really depends on the quality of water we are getting as we travel. Basically if we see the water flow decrease noticeably, or its been about 2 months, we clean it. We just use a hard bristle brush and clean water, takes about 5 minutes to take it out, clean it, and replace it.

We typically use a candle for about 1 year, and then replace it. It may last longer, but we figure ~$40/year is OK for us to spend on a new filter. We have never really noticed any deterioration from the cleaning itself. The material is a hard ceramic, not paper.

The filter we use is the Ultracarb or Supercarb depending on availability.

This specs state 600 gallons/6 months for the Ultracarb, but as I said we only change it 1x year and all has been fine. We drink our water from the tank exclusively, and it always tastes good to us, and much better then water-maker water we have when visiting friends.

We have only a mesh water strainer between the tank and the pump, but this is to keep bigger debris out of the pump, so not really any pre-filtration as far as drinking the water is concerned.

Please describe what we are seeing here. I am guessing that the Whale freshwater supply pump discharge is the black rigid line on the right, just below the vee berth surface, which sweeps around to the back of the filter assembly. You also have a drop down to an (open) ball valve, a strainer and then a drain hose??? For winterizing?? The outflow of the filter appears to be the blue PEX on the left.

Do you require 10" + clearance below the blue filter housing to remove the element? Are the PEX fittings also from Whale. Are they hand tightened compression fittings. Any issues with them? Typical commercial PEX fittings are metal rather than plastic. How do you address vibration/pulsing from the pump with the semi-rigid PEX rather than flexible hose?

Thanks! Enjoying the discussion.

By the way, US Plumbing Codes have required for years that new potable water piping systems be sterilized at 50 ppm for 24 hours, or 200 ppm for 3 hours. I can provide a source if required

The picture is under the salon settee of a catamaran; we really don't have V-berths (very skinny up there).

The flow is from the drop-down (tank), through the open valve and strainer and into the pump. The Whale pump discharges toward the bottom of the picture, out of sight. Between the strainer and the pump is a T for winterizing, with a vinyl hose with pink stuff still in it, attached. Note that this is also handy for sanitizing, if you only want to treat the piping (if you have an aluminum tank).

The pump discharge then goes to a pressure tank, splits in to hot/cold and several locations (all out-of-sight), and then returns from the bottom of the picture in blue 15mm PE pipe. The fittings are Whale quick connects and have proven durable and easy to work with. They are 1997 and zero leaks. They can be disconnected with only you fingers. Pulsation has not been a problem,

In the picture I have a 5" housing (not recommended unless space is very tight--just slow). I later switched to a 10" housing to get better flow (Pentek floplus-10, 1.3 gpm at 35 psi). You need only about 1.5 inches of clearance under the bowl to remove the cartridge and should not spill more than a teaspoon if cautious. Though it is only hand tight, an oil filter wrench is handy if it gets stuck. Do Vaseline the o-ring.

This filter serves only the galley sink. If I were going whole-boat I would probably chose a Doulton Rio-2000 (9 gpm).

Some folks do a separate tap for the filter; if part of the concern is microorganisms, why would I want to wash dishes with unfiltered water, just to save a little filter life? It's not like home where people really flow some water doing dishes and where the water is inherently trustworthy.

Yeah, please supply the code ref. I know the code of RV and boats, but that would be interesting.

This is from the 1993 BOCA Plumbing Code, simply because I could grab it quickly. I personally recall this requirement going back perhaps 30 years or more.

Similar, if not identical, sections have been included with the UPC, Southern, ICBO and various other "model" codes. Additionally, various local, municipal jurisdictions (New York City has its own code, for example) use this as do Federal Agencies and military construction projects.

In projects I have overseen, the Contractor has been required to provide written verification of successful completion of sterilization prior to final payment.

“SECTION P-1509.0 DISINFECTION OF POTABLE WATER SYSTEM

P-lS09.1 General: New or repaired potable water systems shall be purged of deleterious matter and disinfected prior to utilization. The method to be followed shall be that prescribed by the health authority having jurisdiction or, in the absence of a prescribed method, the procedure described in either AWWA C651 or AWWA C652 …[portion deleted]

1. The pipe system shall be flushed with clean, potable water until dirty water does not appear at the points of outlet.

2. The system or part thereof shall be filled with a water/chlorine solution containing at least 50 parts per million (50 mg/l) of chlorine, and the system or part thereof shall be valved off and allowed to stand for 24 hours; or the system or part thereof shall be filled with a water/chlorine solution containing at least 200 parts per million (200 mg/l) of chlorine and allowed to stand for 3 hours.

3. Following the required standing time, the system shall be flushed with clean potable water until the chlorine is purged from the system.

4. The procedure shall be repeated where shown by a bacteriological examination that contamination remains present in the system.”

By the way, specialized facilities (laboratories, health care, etc.) have far more stringent requirements including use of "cleaned and capped" piping, specialized solder, dissolved solids limits, etc. In fact I have, on occasion, dealt with glass piping to meet system requirements. On the high end of research, there are some systems that would take your breath away. Well, maybe not that extreme

The picture is under the salon settee of a catamaran; we really don't have V-berths (very skinny up there).

The flow is from the drop-down (tank), through the open valve and strainer and into the pump. The Whale pump discharges toward the bottom of the picture, out of sight. Between the strainer and the pump is a T for winterizing, with a vinyl hose with pink stuff still in it, attached. Note that this is also handy for sanitizing, if you only want to treat the piping (if you have an aluminum tank).

I was curious if that might have been a bypass for the filter to avoid glycol entering the assembly. This is why I like "flow diagrams". Pics sometimes are not worth a thousand words.

The pump discharge then goes to a pressure tank, splits in to hot/cold and several locations (all out-of-sight), and then returns from the bottom of the picture in blue 15mm PE pipe. The fittings are Whale quick connects and have proven durable and easy to work with. They are 1997 and zero leaks. They can be disconnected with only you fingers. Pulsation has not been a problem,

My sense is that small boats should operate under minimal operating pressure, say 25-35 psi. Lower psi equals lower flow rate (less consumption) and that works for limited water tankage. Less stress on piping, fittings, etc. too. With a filter element rated at 9 gpm, my single operating outlet is likely flowing 1.5 gpm or less and will lead to longer service life and less frequent filter service. Additionally, the slower the water passes through the filter, the less likely is any water bypassing the element (all filters let some water/air/particulate sneak through), as well as improving the likelihood of capturing the smaller particulates.And maybe that equates to annual or better element replacement.

In the picture I have a 5" housing (not recommended unless space is very tight--just slow). I later switched to a 10" housing to get better flow (Pentek floplus-10, 1.3 gpm at 35 psi). You need only about 1.5 inches of clearance under the bowl to remove the cartridge and should not spill more than a teaspoon if cautious. Though it is only hand tight, an oil filter wrench is handy if it gets stuck. Do Vaseline the o-ring.

This filter serves only the galley sink. If I were going whole-boat I would probably chose a Doulton Rio-2000 (9 gpm). I will look at that unit.

Some folks do a separate tap for the filter; if part of the concern is microorganisms, why would I want to wash dishes with unfiltered water, just to save a little filter life? It's not like home where people really flow some water doing dishes and where the water is inherently trustworthy.

My first thought was to include just the cold water service to be filtered, but then I thought that I might introduce contaminants due to the single handle sink faucets I have which blend the cold and hot water. My second thought was that I am over thinking this! Final thought was to include the entire potable system, cold and hot, as this also simplifies the install.

Yeah, please supply the code ref. I know the code of RV and boats, but that would be interesting.

My interest in this is that we have had occasional issues with water, especially in the Caribbean, where often we have taken on water from cisterns or other questionable sources. Having the water out of the faucet suddenly turn an interesting yellow color caught our attention. I have also added a small amount (teaspoon?) of chlorine to our water tanks as prophylactic. Most of the time it works.

Looking forward to your upcoming articles in PS I hope others have also gotten something out of this discussion. If not, my apologies to the OP.

^^ Thanks. I'll have to check the IBC too. never thought to look at the dirt side codes.

Clearly, when winterizing the carbon elements come out. Additionally, the clear strainer cover comes off; notice that it is crazed, cause by PG exposure (I proved that by exposing the same clear bowl to both EG and PG for a prior article--PG is a pain in terms of materials compatibility).

I like the carbon block filters for most sailors (week end warriors); we will generally replace the element annually anyway. However, ceramic filters (Doulton) have a lot going for them for live-aboards and those going foreign. The down side of ceramic is cost (reasonable if you clean them a few cycles) and no chemical or chlorine removal. While the latter won't matter for shower or WC use, I might add a cheap carbon filter in galley, or maybe even a carbon block, to get better taste. Yes, there is significant pressure drop, but if the ceramic is a RIO-2000 (9.8 gpm) in front of a carbon block (1 gpm), unless every faucet is running at the same time, the ceramic filter is not flowing hard.

The down side of ceramic is cost (reasonable if you clean them a few cycles) and no chemical or chlorine removal. While the latter won't matter for shower or WC use, I might add a cheap carbon filter in galley, or maybe even a carbon block, to get better taste.

The Ultracarb candle I mentioned previously has a carbon element built into it.

We drink this water 100%, and it tastes perfect, in our opinion of course.

^^ Chlorine removal with carbon is generally long-lived, when there is a good filter in front of it (chlorine is removed by chemical reaction, not adsorption). However, any chemical removal will be limited by the amount of carbon.

So what I wonder is whether the Ultracarb (about $50) or the Floplus-10 (about $12) represent the better value, when lifespan is considered? Surely the extent of pre-filtration matters, as the Doulton unit is cleanable. On the other hand, the Floplus contains more carbon (double). I suspect the result depends on the test method or actual use, and the user preference on whether they would rather clean or replace. I'm guessing the ceramic is better for the full-time user going far afield, and the Floplus for the more occasional user staying closer to home.

I'm quite certain both deliver bottled water quality output, having used both. These are good units.

What has seemed to me to be the weak link in these systems is the hose with which we fill the tanks.

I try to have a dedicated hose for this purpose, which, following use, is emptied of standing water, connected end-to-end, and returned to the hot lazarette to breed bacteria in the warm damp confines of the hose.

Are there any better choices in supply hoses other than simply NSF listed? I will use an end-of-hose filter, but that is primarily for particulates. Suggestions?

What has seemed to me to be the weak link in these systems is the hose with which we fill the tanks.

I try to have a dedicated hose for this purpose, which, following use, is emptied of standing water, connected end-to-end, and returned to the hot lazarette to breed bacteria in the warm damp confines of the hose.

I agree the hoses need care, too. I too empty the dedicated hoses (one specifically for supply to filters, the other specifically for filters to tank fill), and try to let them dry completely before storage. (I can hang them from the flying bridge for a couple days, for positive drainage.)

Once dry, I don't connect them into a closed system, though... on the theory that free air flow might be better. Just guessing...

^^ There is little question that the hose is a major issue in terms of solids load, though I'm not sure how much it contributes to pathenogens if the source water is safe. The solids will be algae and harmless bacteria. But all of that leads to the wrong sort of tank environment.

This came from a single 80 gallon fill from a white hose in regular use; I was moving the hose during the process, to knock stuff loose. This is a 4" diameter filter.I also think this makes dock-mounted filters appear ludicrous. The filter must be at the end of the hose!

I don't think the quality of hose matters in regard to growth. The NSF certification on hoses does NOT mean that nothing will grow. It means that the plastic will not leach harmful chemicals into the water. I'm also not convinced that white is the best color for drinking water hoses, as that encourages algae growth, without enough UV to inhibit bacteria. In fact, white is NOT the only color, it is just popular because it looks "sanitary."